British Pat. No. 2,091,745 describes a process for the manufacture of ethylene terpolymers comprising moieties derived from a (meth)acrylic ester and moieties derived from maleic anhydride, by copolymerization under high pressure, in the presence of at least one free-radical initiator, of a mixture of ethylene, (meth)acrylic ester and maleic anhydride. In this process, the introduction of the (meth)acrylic ester and maleic anhydride monomers into the polymerization reactor is carried out by pumping a solution of maleic anhydride in the (meth)acrylic ester under pressure, mixing this solution with the ethylene stream and homogenizing this mixture before it is fed into the polymerization reactor, the said homogenization being carried out in a venturitype homogenizer and then in a spiral homogenizer.
The applicant has found, in a surprising manner, that in such a process for the manufacture of ethylene terpolymers comprising moieties derived from a (meth)acrylic ester and moieties derived from maleic anhydride, the (meth) acrylic ester and maleic anhydride monomers could be introduced into the polymerization reactor by being fed directly into the said reactor.